Field of the Invention
The present invention refers to a recirculating system for a fuel supply system for a motor and to a method for supplying fuel to a motor of a vehicle through such a supply system.
Fuel supply method according to the invention can be advantageously used for supplying different fuels such as LPG, DME, ammonia and similar fuels.
The above method can be further advantageously used for supplying direct or indirect injection, traditional injection or common rail injection gasoline and diesel motors.
In the following the specification will be addressed to a supply system and to a supply method for a gasoline and LPG motor of a vehicle, but it is well evident that the same must not be considered limited to the use with this type of specific fuels, being it possible using them also with fuels different with respect to those indicated in the following specification.
Brief Discussion of the Related Art
In vehicles provided with a gasoline or diesel supplied with a traditional LPG supply system, LPG to be always maintained at the liquid state, if not used by the motor, must necessarily return to the tank to prevent its gasification and thus it occurs that when the vehicle is running, LPG contained within the vehicle tank tends to progressively increase its temperature due to the residual LPG that, from high pressure pump or from injector rail returns, hot, to the tank.
For example, it is observed that after a journey of only some hours. LPG temperature within the vehicle tank could even pass 70° C.
Increase of LPG temperature within the tank unavoidably means a corresponding increase of pressure, up to pressure values that could even pass maximum allowed threshold (20 bar) for delivering LPG by LPG station to make supplying.
Therefore, in case LPG pressure within the vehicle tank passes the above threshold, it would be absolutely impossible supplying LPG.
At present, average LPG delivery pressure in LPG station is usually within the range between 12 bar and 15 bar.
This means that if pressure of LPG within the vehicle tank passes 15 bar, station pump cannot transfer LPG to the tank.
Recently it has been thought overcoming said problem by controlling a temporary switching of motor supply from LPG to gasoline, when an excessive LPG temperature increase occurs, in order to obtain a progressive lowering of the temperature, and thus of the LPG pressure within the tank until when the motor is supplied with gasoline.
However, in this case the driver would be obliged to make one or more parts of his/her journey with motor supplied with gasoline instead that with LPG, as he/she could prefer to reduce fuel costs.